Downhole seal and anchor releasing system and method

ABSTRACT

A downhole seal and anchor releasing device includes, a seal defeatable via a first pull, an anchor releasable via a second pull, and an energy dissipation device configured to dissipate enough energy from the first pull subsequent defeat of the seal to prevent release of the anchor in response to the first pull

BACKGROUND

It is common in the hydrocarbon recovery industry to anchor a tool or tubular from a downhole location and to also seal off the borehole at or near the anchor point. One such example is at a whipstock where one leg of the well is sealed off while another leg remains open, for example, to allow continued production. At times, it is desirable to remove both the seal and the anchor. When doing so, however, it may be desirable to equalize any pressure differential across the seal and even release the seal itself, prior to releasing the anchor to prevent excessive movement of the tool that could result during the sudden pressure equalization process if the anchor is released prior to equalization of the pressure. Devices and methods that provide for separate pressure equalization and release control of the seal and the anchor would be well received in the art.

BRIEF DESCRIPTION OF THE INVENTION

Disclosed herein is a downhole seal and anchor releasing device. The device includes, a seal defeatable via a first pull, an anchor releasable via a second pull, and an energy dissipation device configured to dissipate enough energy from the first pull subsequent defeat of the seal to prevent release of the anchor in response to the first pull.

Further disclosed herein is a downhole seal and anchor releasing method. The method includes, defeating the seal with a first pull, dissipating energy subsequent to defeating of the seal such that energy remaining from the first pull is below an energy threshold required to release the anchor, and releasing the anchor with a second pull.

Further disclosed herein is a downhole seal and anchor releasing system. The system includes, a seal sealably engagable with a downhole structure, a valve in functional communication with the seal configured to bypass the seal in response to a first pull, an anchor engagable with the downhole structure and releasable with a second pull, and an energy dissipation device configured to dissipate energy from the first pull sufficient to prevent release of the anchor subsequent to the first pull and advance of the second pull.

BRIEF DESCRIPTION OF THE DRAWINGS

The following descriptions should not be considered limiting in any way. With reference to the accompanying drawings, like elements are numbered alike:

FIGS. 1A-1B depict a partial cross sectional view of a downhole seal and anchor releasing device disclosed herein in a configuration sealed and anchored to a tubular;

FIGS. 2A-2B depict a partial cross sectional view of the downhole seal and anchor releasing device of FIGS. 1A-1B illustrated in a configuration sealed and anchored to a tubular while equalizing pressure across the seal;

FIGS. 3A-3B depict a partial cross sectional view of the downhole seal and anchor releasing device of FIGS. 1A-1B illustrated in a configuration with the seal and the anchor released from engagement with a tubular;

FIGS. 4A-4B depict a partial cross sectional view of an alternate embodiment of a downhole seal and anchor releasing device disclosed herein in a configuration sealed and anchored to a tubular;

FIGS. 5A-5B depict a partial cross sectional view of the downhole seal and anchor releasing device of FIGS. 4A-4B illustrated in a configuration anchored to a tubular with the seal released from sealing engagement with the tubular; and

FIGS. 6A-6B depict a partial cross sectional view of the downhole seal and anchor releasing device of FIGS. 4A-4B illustrated in a configuration with the seal and the anchor released from engagement with the tubular.

DETAILED DESCRIPTION OF THE INVENTION

A detailed description of one or more embodiments of the disclosed apparatus and method are presented herein by way of exemplification and not limitation with reference to the Figures.

Referring to FIGS. 1A-3B an embodiment of the seal and anchor releasing device 10, disclosed herein, is illustrated in various conditions of actuation. In FIGS. 1A-1B, for example, the device 10 is sealed and anchored downhole to wellbore walls 14, such as the walls of a liner, casing, open hole or other tubular, for example. The releasing device 10, among other things includes, a seal 18, an anchor 22 and an energy-dissipation device 26 disposed at a mandrel 30. FIGS. 2A-2B illustrate the energy-dissipation device 26 in a pressure equalizing configuration to allow pressure to equalize across seal 18. And FIGS. 3A-3B illustrate the device 10 with neither the seal 18 nor the anchor 22 engaged with the walls 14. Embodiments disclosed herein provide for control to equalize pressure across a seal, thereby defeating the seal, while maintaining engagement of the seal 18 and the anchor 22 with the walls 14. Additional embodiments disclose releasing the seal 18 from engagement with the walls 14 while maintaining engagement of the anchor 22 with the walls 14. These tasks are difficult, if not impossible, with existing systems since the dynamic and sudden release of energy that occurs with the release or defeat of the seal 18 will often cause the anchor 22 to release as well. This condition is exacerbated in horizontal or highly deviated wells where threshold forces to release an anchor are limited from being set at values much greater than threshold forces to release a seal. This limitation is due to the high frictional forces between the drillstring and the walls 14 that limit pull forces that can be applied to downhole tools.

Embodiments described herein address this issue by incorporation of the energy dissipation device 26. In the first embodiment the energy dissipation device 26 dissipates energy after initiation of pressure equalization and before release of the seal 18 and anchor 22, so that any remaining energy is unable to exert forces on the seal 18 and anchor 22 that are greater than a release force threshold necessary to release the seal 18 and anchor 22. In so doing, the device 10 allows an operator to separately control the pressure equalization process from the release of the seal 18 and release of the anchor 22. A detailed review of the device 10 follows.

In the embodiment of FIGS. 1A-3B, the seal 18 includes a plurality of packing elements 34 that sealably engage with the walls 14 when in an actuated condition and permit fluid leakage between the seal 18 and the walls 14 when in a non-actuated condition. The anchor 22 includes slips 38 that fixedly anchor the releasing device 10 to the walls 14 when in an actuated condition and allow movement of the releasing device 10, relative to the walls 14, when in a non-actuated condition. The energy-dissipating device 26 includes energy-storing members 42 and energy-absorbing members 43. In this embodiment the energy-storing members 42 are compression springs, and the energy-absorbing members 43 include a piston 44, which forces fluid through an opening 45, and cup springs, which are commonly referred to as Belleville™ (Trademark) washers. Although the opening 45 is illustrated herein as being in a wall, alternate embodiments could incorporate the opening in the piston 44. Additionally, it should be noted that embodiments including just one or the other of the energy-storing members 42 and the energy-absorbing members 43 may be used. Additionally, the energy-dissipating device 26 may include other energy-storing members 42, as well as other energy-absorbing members 43, such as deformable members (as in crushable tubulars), for example.

Referring to FIGS. 2A-2B, the device 10 is illustrated in a condition sealed and anchored to the walls 14 while allowing pressure to equalize across the seal 18 through an internal bypass valve 46. The bypass valve 46 allows wellbore fluid to flow between a downhole annular space 50 and an uphole annular space 54 via an internal bore 58 of the mandrel 30. The annular spaces 50 and 54 are defined by a space between the walls 14 and upper cone adapter 62 and the walls 14 and an upper seal housing 66 respectively. Fluidic communication between the annular spaces 50 and 54 is controlled through the control of alignment of two sets of ports. A lower set of ports includes ports 70 through the upper cone adapter 62, ports 74 through an inner sleeve 78 and ports 82 through the mandrel 30. An upper set of ports includes ports 86 through the upper seal housing 66, ports 90 through the inner sleeve 78 and ports 94 through the mandrel 30. The mandrel 30 is movable relative to the inner sleeve 78 such that the ports 74 are misaligned with the ports 82, and the ports 90 are misaligned with the ports 94, when the mandrel 30 is positioned in a downhole direction with respect to the inner sleeve 78, as is the position shown in FIGS. 1A-1B. Alternately, FIGS. 2A-2B show the mandrel 30 in an uphole direction relative to the inner sleeve 78 such that the ports 74 are aligned with the ports 82 and the ports 90 are aligned with the ports 94, such that fluid is able to flow from the annular space 50 to the annular space 54 via the following; ports 70, 74, 82, through the bore 58 and out through the ports 94, 90 and 86.

Movement of the mandrel 30 relative to the inner sleeve 78 (and the device 10) can be controlled from surface. A coupling 96, on an uphole end of the mandrel 30, can be connected to a drillstring (not shown), for example, that extends to surface. With such connection, the mandrel 30 can be pulled from the surface via the drillstring. In the present embodiment, with the seal 18 in sealing engagement with the walls 14 and the anchor 22 anchored to the walls 14, a pull on the mandrel 30, from surface, can cause the mandrel 30 to move from a position wherein fluidic communication between the annular spaces 50 and 54 is blocked to a position wherein the fluidic communication between the annular spaces 50 and 54 is allowed, as described above. Such movement of the mandrel 30 relative to the inner sleeve 78 may, however, be prevented until a force of the pull exceeds a threshold required to cause a force failing member 98 (illustrated in this embodiment as a shear ring) to fail. This shear ring 98 can prevent unintentional actuation of the bypass valve 46, until desired, by requiring a specified pull force threshold to be attained to shear the shear ring 98.

The pull force required to shear the shear ring 98, however, causes energy to be stored in the elasticity of the length of drillstring between the device 10 and surface. As the shear ring 98 fails and the drillstring recoils, some of the energy, stored in the drillstring, is converted into kinetic energy. This recoil action can create a hammering effect on a second force failing member 102, disclosed in this embodiment as a release stud 102 that is designed to release both the seal 18 and the anchor 22 in response to a pull having a force greater than a selected threshold. If not for the inclusion of the energy-dissipating device 26, disclosed in embodiments herein, the dynamic nature of the hammering action from the recoil could result in sufficient force (applied over a short time duration) to exceed the threshold force of the release stud 102 causing an undesirable failure and premature release of the seal 18 and the anchor 22. It is the inclusion of the energy-dissipating device 26; therefore, that prevents such premature and undesirable failure.

A review of FIGS. 1A-1B to 2A-2B reveals how the energy-dissipating device 26 achieves the desired function. In FIGS. 1A-1B a pull from surface on the mandrel 30 applies a load to the shear ring 98 and not to the release stud 102. When such force of the pull exceeds a failure threshold of the shear ring 98, the shear ring 98 will fail. After failure of the shear ring 98, the release stud 102 that is fixedly attached to the mandrel 30 by such means as a threadable engagement, for example, begins moving in an uphole direction with the mandrel 30. A head 106 of the release stud 102 moves the piston 44 and simultaneously compresses the cup washers 42. During compression, the cup washers 42 store some of the energy and convert some of the energy into heat through internal friction resulting from deformation of the cup washers 42. Additionally, movement of the piston 44 within a chamber 110 defined by a lower cone 114 within which it is housed, pressurizes fluid 118, such as oil, grease or water, for example, within the chamber 110. The pressurized fluid 118 is pumped through the opening 45 or through clearance between the piston 44 and the lower cone 114. Regardless of where the pressurized fluid 118 escapes, energy is absorbed during the process of the fluid 118 flowing. The loss of energy from the recoil of the drillstring results in a reduction in velocity of the mandrel 30. This reduction in velocity of the mandrel 30 decreases forces encountered within the release stud 102 as the release stud 102 approaches a maximum uphole travel position limited by the energy dissipation device 26. The energy dissipation device 26 thereby, when applied correctly, softens the hammering effect of the recoil of the drillstring on the release stud 102 to a point that the release stud 102 does not fail in response to the recoil.

Continuing reference to FIGS. 2A-2B, additional upward travel of the mandrel 30 relative to the device 10 is possible after failure of the release stud 102. The release stud 102 is made to fail by an upward pull on the mandrel 30 from the drillstring that creates a pull force in excess of a force failing threshold of the release stud 102. In embodiments disclosed herein the force failing threshold for the release stud 102 is less than twice that of the force failing threshold of the shear ring 98. This is possible since a pull on the device while both the shear ring 98 and the release stud 102 are intact causes only the shear ring 98 to be loaded and not the release stud 102 as discussed above. Additionally, the energy dissipation device 26 absorbs energy of the drillstring recoil such that the force failing threshold of the release stud 102 is not achieved subsequent failure of the shear ring 98. After failure of the shear ring 98 a second pull from surface causes the mandrel 30 and the release stud 102 to travel upward with respect to the anchor 22 thereby allowing the release stud 102 to experience all of the force of the second pull until it fails.

After the release stud 102 has failed, additional movement of the mandrel 30, in an uphole direction, causes a shoulder 122 on the mandrel 30 to contact a key 126 that is fixed to the inner sleeve 78, thereby causing the inner sleeve 78 to move in an uphole direction. Engagement of the inner sleeve 78 with a shoulder 80 of the upper seal housing causes the upper seal housing 66, to move uphole also. Movement of the upper seal housing 66 in an uphole direction moves an upper guide ring 130, attached thereto, in an uphole direction and away from a lower guide ring 134, located on a downhole side of the seal 18. This separational movement of the two guide rings 130, 134 reduces axial compression of the packing elements 34 of the seal 18 from the two guide rings 130, 134 causing the packing elements 34 to reduce a radial dimension thereof until the seal 18 is no longer in sealing engagement with the walls 14. Alternate embodiments of the present invention can rely directly upon disengagement of the seal 18 from the walls 14 to equalize any pressure differential thereacross instead of utilizing the bypass valve 46 described above. Such an embodiment is described below with reference to FIGS. 4A-6B.

Referring to FIGS. 3A-3B, the device 10 is illustrated with both the seal 18 and the anchor 22 released from the walls 14. Continued upward movement of the mandrel 30, after the seal 18 has released, causes the inner sleeve 78 to continue to move upward also. The upward movement of the inner sleeve 78 causes an upper cone 138, through a key engaged therebetween (not shown), to move upward and away from the lower cone 114. The separation of the upper cone 138 from the lower cone 114 allows slips 150 to recede radially under the forces of slip spring 154, thereby releasing the anchor 22 from the walls 14.

Referring to FIGS. 4A-6B, an alternate embodiment of a releasing device 210 is illustrated. The device of 210 is similar to the device 10 and as such similar items are designated with the same reference characters. A primary difference between the two devices 10, 210 is that the device 210 releases differently than the device 210. The device 210 equalizes pressure across the seal 18 upon radial reduction of the packing elements 34 that breaks a seal between the packing elements 34 and the walls 14, instead of through an internal bypass valve 46 as in the first embodiment. The device 210 includes two force failing events, the first to release the seal 18 and the second to release the anchor 22. The first force failing event requires the shear ring 98 to fail and the second force failing event requires both a release stud 158 and shear screws 162 to fail. An energy dissipation device 166 dissipates enough residual energy in the drillstring to prevent the second force failing event from occurring in response to the sudden release of the residual energy.

Referring to FIGS. 4A-4B, the device 210 is illustrated in a condition with both the seal 18 and the anchor 22 engaged with the walls 14. An upward pull on the mandrel 30 first loads the shear ring 98 without loading either of the release stud 158 or the shear screws 162. Upon shearing of the shear ring 98 the mandrel 30 is able to move upward relative to the seal 18 and lifts the upper seal housing 66 that lifts the upper guide ring 130. As the upper guide ring 130 moves away from the lower guide ring 134 the packing elements 34 compressed therebetween are able to contract radially to disengage from the walls 14 and allow equalization of pressure thereacross.

As the shear ring 98 fails in response to the force of the pull, the energy stored in the elasticity of the drillstring is released in recoil. The recoil urges the mandrel 30 to move upward at a high rate that is prevented by the energy dissipation device 166. The energy dissipation device 166 includes a piston 170 that is attached to the release stud 158 through threadable engagement or welding, for example. The piston 170 is housed within a chamber 174 defined by the lower cone 178. One or more opening(s) 182 in the lower cone 178 allow the fluid 118 located in the chamber 174 to be pumped from the chamber 174 at a controlled rate. The controlled flow rate of fluid 118 slows the rate of upward movement of the piston 170 thereby decreasing the hammering effect as a travel distance of the piston 170 is exhausted, thereby preventing failure of the release stud 158 and the shear screws 162 from the first pull.

Referring to FIGS. 5A-5B, the device 210 is illustrated with the seal 18 released and the anchor 22 engaged with the walls 14. The shear ring 98 is sheared but the release stud 158 and the shear screws 162 are still intact. A second upward pull on the mandrel 30 causes both the release stud 158 and the shear screws 162 to become loaded. Alternate embodiment may use a single force failing member such as only the release stud 158. Upon application of a sufficient load, the release stud 158 and the shear screws 162 will both fail, thereby allowing the mandrel 30 to move upward relative to the anchor 22. This additional upward movement of the mandrel 30 causes the inner sleeve 78 to continue to move upward also. The upward movement of the inner sleeve 78 causes an upper cone 186, through a key engaged therebetween (not shown), to move upward and away from the lower cone 178. The separation of the upper cone 186 from the lower cone 178 allows the slips 150 to recede radially under the forces of slip spring 154, thereby releasing the anchor 22 from the walls 14.

While the invention has been described with reference to an exemplary embodiment or embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the claims. Also, in the drawings and the description, there have been disclosed exemplary embodiments of the invention and, although specific terms may have been employed, they are unless otherwise stated used in a generic and descriptive sense only and not for purposes of limitation, the scope of the invention therefore not being so limited. Moreover, the use of the terms first, second, etc. do not denote any order or importance, but rather the terms first, second, etc. are used to distinguish one element from another. Furthermore, the use of the terms a, an, etc. do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced item. 

1. A downhole seal and anchor releasing device, comprising: a seal defeatable via a first pull; an anchor releasable via a second pull; and an energy dissipation device configured to dissipate enough energy from the first pull subsequent defeat of the seal to prevent release of the anchor in response to the first pull.
 2. The downhole seal and anchor releasing device of claim 1, wherein the seal and anchor are in operable communication with a whipstock.
 3. The downhole seal and anchor releasing device of claim 1, further comprising a bypass valve configured to equalize pressure across the seal prior to release of the seal from sealing engagement with a tubular.
 4. The downhole seal and anchor releasing device of claim 1, wherein the seal is configured to equalize pressure thereacross in response to being released prior to release of the anchor.
 5. The downhole seal and anchor releasing device of claim 1, wherein a force threshold to release the anchor less than twice a force threshold to defeat the seal.
 6. The downhole seal and anchor releasing device of claim 1, wherein the energy dissipation device includes at least one of a spring, a fluid dampener and a crushable member.
 7. The downhole seal and anchor releasing device of claim 6, wherein the spring is a cupped spring washer.
 8. The downhole seal and anchor releasing device of claim 6, wherein the fluid dampener includes a chamber with fluid therein and at least one opening in the chamber for escape of the fluid from the chamber in response to a piston moving within the chamber.
 9. The downhole seal and anchor releasing device of claim 8, wherein the fluid is at least one of, oil, grease and water.
 10. The downhole seal and anchor releasing device of claim 1, further comprising a first force failing member for releasably positioning the seal and a second force failing member for releasably positioning the anchor.
 11. The downhole seal and anchor releasing device of claim 1, wherein at least one of the first pull and the second pull are from surface.
 12. A downhole seal and anchor releasing method, comprising: defeating the seal with a first pull; dissipating energy subsequent to defeating of the seal such that energy remaining from the first pull is below an energy threshold required to release the anchor; and releasing the anchor with a second pull.
 13. The downhole seal and anchor releasing method of claim 12, wherein the dissipating energy includes increasing stored energy of an energy storing member.
 14. The downhole seal and anchor releasing method of claim 12, wherein the dissipating energy includes pressurizing a fluid and flowing at least a portion of the pressurized fluid through at least one opening.
 15. The downhole seal and anchor releasing method of claim 12, wherein the dissipating energy includes crushing a crushable member.
 16. The downhole seal and anchor releasing method of claim 12, further comprising decreasing a pressure differential across the seal subsequent to release of the seal and prior to release of the anchor.
 17. The downhole seal and anchor releasing method of claim 12, wherein a force of the second pull is less than twice a force of the first pull.
 18. The downhole seal and anchor releasing method of claim 12, wherein defeating the seal includes failing a force failing member.
 19. The downhole seal and anchor releasing method of claim 12, wherein releasing the anchor includes failing a force failing member.
 20. A downhole seal and anchor releasing system comprising: a seal sealably engagable with a downhole structure; a valve in functional communication with the seal being configured to bypass the seal in response to a first pull; an anchor engagable with the downhole structure and releasable with a second pull; and an energy dissipation device configured to dissipate energy from the first pull sufficient to prevent release of the anchor subsequent to the first pull and advance of the second pull. 